Controller Flight Into Terrain (CFIT) is one of the leading causes of aviation accidents. When pilots lack situational awareness, it is possible to fly an aircraft, under control, into the ground. CFIT can occur in a number of circumstances. During Instrument Approaches, if a pilot falls below the target flight path, the aircraft may collide with terrain or other obstructions. However, many CFIT incidents also occur in clear weather. In these incidents, pilot distraction or unfamiliarity with a particular airport may cause a CFIT accident to occur.
The risk of such accidents can be greatly reduced through the installation of CFIT avionics, which warn the flight crew when they are at risk of a CFIT accident. However, such avionics are cost-prohibitive for installations on smaller aircraft, including typical general aviation aircraft. In such aircraft, additional aviation electronics adds to the weight and clutter of the cockpit area.
While there are CFIT systems available on the market, such as those from Honeywell Corporation (www.honeywell.com), they all rely upon the aircraft being equipped with a specific device known as a ground proximity warning system. Ground proximity warning systems rely on the combination of an on-board terrain database, an accurate navigation system, and logic to estimate potential collisions with the ground or terrain. If the on-board database is not current, then a proper proximity warning may not be given. Thus, for example, if a tower or building is recently constructed near an airport, and the database on the plane is not updated to reflect this new addition, the system might not provide a warning when a collision with such an object is imminent.
Other relevant Honeywell references include: U.S. Pat. No. 6,606,034, issued Aug. 12, 2003, entitled, “Terrain awareness system”; U.S. Pat. No. 6,571,155, issued May 27, 2003, entitled, “Assembly, computer program product and method for displaying navigation performance based flight path deviation information”; U.S. Pat. No. 6,477,449, issued Nov. 5, 2002, entitled “Methods, apparatus and computer program products for determining a corrected distance between an aircraft and a selected runway”; U.S. Pat. No. 6,469,664, issued Oct. 22, 2002, entitled “Method, apparatus, and computer program products for alerting surface vessels to hazardous conditions”; U.S. Pat. No. 6,445,310, issued Sep. 3, 2002, entitled “Apparatus, methods, computer program products for generating a runway field clearance floor envelope about a selected runway”, U.S. Pat. No. 6,380,870, issued Apr. 30, 2002, entitled “Apparatus, methods, and computer program products for determining a look ahead distance value for high speed flight”; U.S. Pat. No. 6,347,263, issued Jan. 12, 2002, entitled “Aircraft terrain information system”; U.S. Pat. No. 6,292,721, issued Sep. 18, 2001, entitled “Premature descent into terrain visual awareness enhancement to EGPWS”; and U.S. Pat. No. 6,219,592, issued Apr. 17, 2001, entitled “Method and apparatus for terrain awareness”, all of which are incorporated herein by reference.
Another technique for detection of an aircraft potential collision with terrain is the FAA's Minimum Safe Altitude Warning (MSAW) system where the air traffic controller is notified when the barometric reported altitude of an aircraft falls below a threshold set for the geographic locations of the aircraft, as reported by radar (See: www.FAA.gov). The problem with this system is that it relies upon the barometric pressure calibration on the aircraft transponder of each aircraft. Moreover, the system adds to the load of an air traffic controller if they are required to give verbal warnings. As with any system with a man in the loop, it may be subject to mishap, and moreover any warnings may be given too late.
Moreover, the increased use of electronics in the cockpit has resulted in increased workload for the cockpit crew as various navigation, collision avoidance, and other electronics need to be tended to and monitored. A CFIT system adds to this electronic workload by providing yet another system which a pilot needs to monitor.
Thus, it remains a requirement in the art to provide protection for aircraft not provided with special CFIT avionics or other types of safety monitoring equipment.
In the United States, for example, there are over 2,000 commercial aircraft which are generally well-equipped with avionics devices, but over 200,000 General Aviation Aircraft which are lesser equipped, and would benefit from any system which can make use of ground-based systems which datalink information up to the pilot. Such a system would provide the advantages of state of the art avionics to most of these General Aviation aircraft at a far lower cost than conventional airborne avionics.